Fiber optic based subscriber terminal

ABSTRACT

A subscriber terminal ( 22 ) within a business/residence ( 32 ) is in communications with a telecommunications network ( 12 ) through a fiber optic connection ( 33 ) to an optical network unit ( 20 ). Telephony signals are transmitted to and from the subscriber terminal to a user through a cordless telephone handset ( 26 ). During normal operation, the cordless telephone handset ( 26 ) operates in a cordless mode, passing telephony signals to a subscriber terminal telephone antenna ( 24 ) for transmission on the fiber optic connection ( 33 ). In the event of a power outage at the business/residence ( 32 ), the cordless telephone handset ( 26 ) switches to a wireless mode in order to continue to provide telephony communications. In the wireless mode, telephony communications are provided from the cordless telephone handset ( 26 ) to the telecommunications network ( 12 ) through a wireless telephone provider ( 14 ).

This application is a continuation of U.S. application Ser. No.08/605,944 filed Feb. 23, 1996, now U.S. Pat. No. 5,982,854.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to the field of telecommunicationssystems and more particularly to a fiber optic based subscriberterminal.

BACKGROUND OF THE INVENTION

As the Information Age moves forward and businesses and individualsincreasingly demand and depend on the immediate availability of currentinformation, the reliability of telecommunications systems to deliverthis information becomes critical. Homes and businesses usetelecommunications systems to exchange such information as video, audio,data, telephony, and computer/control information. Reliability oftelecommunications systems becomes of paramount importance as societyrelies more and more on telecommunications systems.

Telecommunications systems using fiber optic cable or copper based highspeed digital drop techniques to transmit telecommunications signals arebecoming increasingly prevalent due to the enormous advantages thatfiber-optic technology provides over conventional analog copper-wirebased systems. Some of these advantages include larger bandwidths andimproved signal quality. A larger bandwidth allows for the transmissionof larger amounts of information over a shorter period of time. Theseand other advantages have made fiber-optic cables the preferredtechnology for exchanging information in telecommunications systems.

Fiber optic technology does suffer at least one disadvantage as comparedto telecommunications systems using conventional copper-wire or wirebased local loop distribution systems. In the event of an electricalpower outage at the home or business, a fiber-optic based local loopdistribution system suffers a complete loss of telephony communicationsunlike a copper-wire based local loop distribution system that receivespower directly from the central office and is able to provide telephonycommunications despite a power outage at the home or business. Eventhough the power outage prevents the operation of televisions, videomonitors, and computers, the telephone continues to operate normally ina copper-wire based system. The telephony communications continuenormally due to the local phone company providing power to the systemthrough the copper-wire phone line, independent of the local powercompany. Thus, even though video and data communications may cease dueto the power outage, telephony or telephone communications may continue.This is not true in a fiber optic based system. Power cannot be suppliedthrough a fiber-optic based local loop distribution system in the samemanner. Thus, a power outage ceases telephony communications in afiber-optic based local loop distribution system.

Telephony communications are especially critical during emergencies,especially police, fire, or medical emergencies demanding immediateattention. Unfortunately, the events surrounding emergencies often causepower outages, such as fires and earthquakes. Thus, fiber optic basedlocal loop distribution systems suffer a significant disadvantage ascompared to copper-wire based local loop systems. Therefore, it isdesirable to overcome the power supply problems of a fiber optic basedsystem.

SUMMARY OF THE INVENTION

From the foregoing it may be appreciated that a need has arisen for afiber optic based subscriber system that may provide telephonycommunications during an electrical system power outage or during theloss of the fiber optic connection to the subscriber system. Inaccordance with the present invention, there is provided a fiber opticbased subscriber terminal and method that substantially eliminate andreduce the disadvantages and problems associated with conventionalsubscriber terminals coupled to a telecommunications network through afiber optic connection.

According to an embodiment of the present invention, a subscriberterminal is provided that includes an external network interface moduleexchanging information, such as video, telephony, and data, with atelecommunications network over a fiber optic connection. A telephonyinterface module exchanges telephony signals with the external networkinterface module and determines if a communication failure occursthrough the fiber optic connection. A handset communicates telephonysignals with the telephony interface module in a cordless mode duringnormal operation. In the event of a communication failure through thefiber optic connection, the handset is switched to a wireless mode forcommunicating with the telecommunications network, bypassing thetelephony interface module and the external network interface module.

The present invention provides various technical advantages over-conventional subscriber terminals using fiber optic based local loopdistribution systems. One technical advantage includes the ability towithstand power outages and other communication interruptions withoutthe loss of telephony communications. Another technical advantageincludes the elimination of expensive power supply equipment, andassociated operational costs, used to provide power to conventionalcopper-wire based local loop distribution systems. The present inventionalso provides a technical advantage over conventional wire orcopper-wire based local loop distribution systems. For example, theability to provide telephony communications in the event: of thecomplete failure or loss of a local loop distribution system provides atechnical advantage over conventional wire based local loop distributionsystems. The present invention also provides the technical advantage ofallowing emergency or 911 calls to be made in the event of a poweroutage or other loss of a local loop distribution system. Othertechnical advantages are readily apparent to one skilled in the art fromthe following figures, description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following description,taken in conjunction with the accompanying drawings, wherein likereference numerals represent like parts, in which:

FIG. 1 is a block diagram illustrating a telecommunications system andnetwork;

FIG. 2 is a block diagram illustrating a subscriber terminal of thetelecommunications system and network;

FIG. 3 is a block diagram illustrating a telephony interface module ofthe subscriber terminal; and

FIG. 4 is a block diagram illustrating a wireless telephone for use withthe subscriber terminal.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram of a telecommunications system 10.Telecommunications system 10 includes a telecommunications network 12, awireless telephone provider 14, and a subscriber terminal 22 locatedwithin a business/residence 32, all in communication with one another.Telecommunications network 12 may be any available public or privatetelecommunications network. Telecommunications network 12 communicateswith subscriber terminal 22 through a telecommunications switch 16, afiber optic local loop distribution system 18, and an optical networkunit 20. Optical network unit 20 couples to subscriber terminal 22 bydirect connection to business/residence 32 through a fiber opticconnection 33. Optical network unit 20 is an optical controller forproviding optical signals to subscriber terminals of various users.These users may be from a few users to a few hundred users. Opticalnetwork unit 20 is supplied with power from the local power company butmay also operate for a limited time through a backup power supply suchas a battery backup.

Subscriber terminal 22 can receive and provide optical communicationsignals including audio, video, data, and telephony communicationsignals. Subscriber terminal 22 includes an in-home local area networkwiring 28 and an in-home television wiring 30 so that data and videosignals may be provided throughout business/residence 32.

Telecommunications network 12 communicates with wireless telephoneprovider 14 through any available direct or wireless communication pathor link 34. Wireless telephone provider 14 may be a cellular, satellite,or personal communications system wireless interface in order totransfer wireless telecommunications. Subscriber terminal 22communicates with wireless telephone provider 14 through a cordlesstelephone handset 26 that can operate as a wireless telephone so thatwireless telephony communication signals may be exchanged betweensubscriber terminal 22 and wireless telephone provider 14.

Cordless telephone handset 26 may operate as a local cordless telephoneor as a wireless telephone. When operating as a local cordlesstelephone, cordless telephone handset 26 exchanges telephony signalswith telecommunications network 12 through subscriber terminal 22.Cordless telephone handset 26 communicates with subscriber terminal 22through subscriber terminal telephone antenna 24. Telephony signals maythen be exchanged between subscriber terminal 22 and telecommunicationsnetwork 12 through optical network unit 20, fiber optic local loopdistribution system 18 and telecommunications system switch 16, whichinterfaces with telecommunications network 12. Cordless telephonehandset 26 may also communicate directly with optical network unit 20through cordless operation with an optical network unit antenna 35.

When operating as a wireless telephone, cordless telephone handset 26provides wireless telephony communication with wireless telephoneprovider 14. Such wireless communications may include cellular,satellite, or personal communications system services. Wirelesstelephone provider 14 includes an antenna 37 for receiving andtransmitting wireless telephony signals to wireless telephone users,including cordless telephone handset 26. Wireless telephone provider 14is in communication with telecommunications network 12 so that cordlesstelephone handset 26 may be in communication with any telephony devicehaving access to telecommunications network 12.

In operation, optical communication signals including video, audio,data, and telephony communication signals are exchanged betweensubscriber terminal 22 and telecommunications network 12 through opticalnetwork unit 20, fiber optic local loop distribution system 18, andtelecommunications switch 16. The telephony communication signals areprimarily exchanged as optical signals using fiber optic cables.Wireless telephony communication is provided between wireless telephoneprovider 14 and a plurality of wireless telephone users. These wirelesstelephone users may exchange telephony signals with non-wirelesstelephone users through telecommunications network 12.

Subscriber terminal 22 receives the optical communication signals androutes them to an appropriate output device of business/residence 32.For example, video signals may be routed through in-home televisionwiring 30. In-home television wiring 30 may be coaxial cable or anyother cable having a sufficient bandwidth. Computer or data signalsreceived by subscriber terminal 22 will be supplied to in-home localarea network wiring 28 which may be coupled to any of a variety ofcomputer devices such as a personal computer. Finally, the telephonycommunication signals will be transmitted via subscriber terminaltelephone antenna 24 to cordless telephone handset 26 operating as alocal cordless phone.

When a power outage occurs at business/residence 32, the opticalcommunication signals, including the telephony communication signals,would cease to be sent or received over fiber optic connection 33 bysubscriber terminal 22. Subscriber terminal 22 requires power to operateand thus could no longer receive any signals. Backup power cannot besupplied by the central office through fiber optic cable as incopper-wire local loop distribution systems. Furthermore, the poweroutage prevents the televisions, video terminals, and personal computersfrom operating. However, cordless telephone handset 26 may be swappedfrom operating as a local cordless phone to operating as a wirelessphone. This allows telephony communications to continue during the poweroutage. Thus, even though a power outage prevents most communication,telephony communications may continue between cordless telephone handset26 and wireless telephone provider 14. The availability of telephonycommunication is especially critical during emergency situations.

As an alternative to the operation just described, when a power outageoccurs, cordless telephone handset 26 may be in local wireless orcordless communication with optical network unit 20. Optical networkunit 20 may operate from a backup power source and include circuitry toexchange local wireless or cordless telephony signals with cordlesstelephone handset 26. The wireless telephony communication signalsexchanged between optical network unit 20 and cordless telephone handset26 may then be exchanged through fiber optic local loop distributionsystem 18 and telecommunications switch 16 to reach telecommunicationsnetwork 12. Alternatively, optical network unit 20 may also includewireless telephone circuitry so that these local wireless telephonysignals may be exchanged with wireless telephone provider 14. Wirelesstelephone provider 14 would then provide access to telecommunicationsnetwork 12.

FIG. 2 is a block diagram of subscriber terminal 22 of thetelecommunications system. Subscriber terminal 22 includesmicrocontroller/microcomputer 40 for controlling an address and data bus42, a packet bus 44, and a time division multiplexing (TDM) bus 46.Address and data bus 42, packet bus 44, and TDM bus 46 exchange signalswith a variety of modules. The modules include a telephony interfacemodule 48, an external network interface module 52, an asynchronoustransfer mode (ATM) cell controller 56, an asynchronous transfermode/motion picture experts group (ATM/MPEG) decoder 58, an in-housevideo signaling unit 62, and a local area network (LAN) controller 64.

External network interface module 52 interfaces with address and databus 24, packet bus 44, and TDM bus 46. External network interface module52 provides all of the incoming and outgoing optical communicationsignals and interfaces with a fiber optic connection 33. Fiber opticconnection 33 exchanges optical communication signals including video,audio, data, and telephony signals between optical network unit 20 andsubscriber terminal 22.

Telephony interface module 48 includes a subscriber terminal cordlesstelephone antenna 24, and interfaces with address and data bus 42 andTDM bus 46. Telephony interface module 48 also couples to in-hometelephone wiring 50. Subscriber terminal cordless telephone antenna 24provides local telephony communication with a cordless telephone such ascordless telephone handset 26 shown in FIG. 1.

ATM cell controller 56, ATM/MPEG decoder 58, and in-house videosignaling unit 62 are used in subscriber terminal 22 to exchange videocommunication signals. ATM cell controller 56 and ATM/MPEG decoder 58couple to address and data bus 42 and packet bus 44 ofmicrocontroller/microcomputer 40. In-house video signaling unit 62 alsocouples to address data bus 42 and packet bus 44. ATM/MPEG decoder 58 isalso in direct communication with in-house video signaling unit 62.ATM/MPEG decoder 58 is used to compress and decompress videocommunication signals and provide them to in-home television wiring 30.In-home television wiring 30 may include coaxial cable.

LAN controller 64 couples to address and data bus 42 and packet bus 44.LAN controller 64 exchanges data signals that are ultimately supplied toin-home LAN wiring 28 for use by personal computers that may beconnected as a computer network.

In operation, external network interface module 52 receives a variety ofoptical communication signals including video, audio, data, andtelephony signals. Telephony signals are then provided to the bus ofmicrocontroller/microcomputer 40. Microcontroller/microcomputer 40controls the exchange and flow of information throughout subscriberterminal 22.

Microcontroller/microcomputer 40 provides and receives various controlsignals to address and data bus 42 to ensure that the variouscommunication signals are properly routed throughout subscriber terminal22. Telephony signals are provided to telephony interface module 48through TDM bus 46. Telephony interface module 48 then provides thetelephony signals to in-home telephone wiring 50 and to subscriberterminal cordless telephone antenna 24 so that telephony signals may beprovided to a local cordless telephone. Telephony interface module 48provides appropriate control signals to address and data bus 42 alongwith telephony signals to TDM bus 46 when telephony signals are beingsent from subscriber terminal 22. These telephony signals are thenprovided to external network interface module 52 which in turn providesthe signals to fiber optic connection 33.

Video communication signals are controlled and provided through thecombination of ATM cell controller 56, ATM/MPEG decoder 58, and in-housevideo signaling unit 62. For example, the control of the exchange ofvideo signals is provided by ATM cell controller 56 while ATM/MPEGdecoder 58 receives the actual video signals from packet bus 44 anddecodes or decompresses the video signals and provides it to in-hometelevision wiring 30 which is coupled to various television receivingunits. In-house video signaling unit 62 is used to provide controlsignals to ATM/MPEG code 58 and microcontroller/microcomputer 40 so thatthe desired video program may be received by subscriber terminal 22.

LAN controller 64 is used to exchange computer data signals betweenpersonal computers coupled to in-home LAN wiring 28 and externalnetworks and computers coupled to a telecommunications system. Theexternal network or computer accesses subscriber terminal 22 throughtelecommunications network 12 which in turn supplies the computer datato external network interface module 52 which when supplies the data toLAN controller 64.

FIG. 3 is a block diagram of telephony interface module 48. Telephonyinterface module 48 includes a bus interface 70, a pulse code modulation(PCM) codec 74, a transceiver 76, a subscriber terminal cordlesstelephone antenna 24, and a wire converter 80. Various control functionsof telephony interface module 48 are performed by a control circuit 72.In operation, telephony signals are exchanged between TDM bus 46 and businterface 70. Address and data bus 42 also couples to bus interface 70to determine when bus interface 70 may receive or provide telephonysignals to TDM bus 46. When receiving telephony signals, TDM bus 46provides telephony signals to bus interface 70 which in turn providesthe telephony signals to PCM codec 74. PCM codec 74 decodes anddecompresses the digital telephony signal and provides a decodedtelephony signal to wire converter 80 so that the telephony signal maybe distributed throughout in-home telephone wiring 50. PCM codec 74 alsoprovides decoded telephony signals to transceiver 76 so that they may betransmitted through subscriber terminal cordless telephone antenna 24 toa local cordless telephone.

When telephony interface module 48 supplies telephony signals, thetelephony signals are received from either in-home telephone wiring 50or through subscriber terminal cordless telephone antenna 24. Thetelephony signals are openly provided to bus interface 70 which in turnprovides the telephony signals to TDM bus 46. Control circuit 72 is usedthroughout the operation of telephony interface module 48 to exchangevarious control and data signals.

FIG. 4 is a block diagram of cordless telephone handset 26. Cordlesstelephone handset 26 includes a speaker 90 and a microphone 92 which maybe a standard telephone handset including a common telephone voicecircuit 94. Cordless telephone handset 26 further includes an in-homecordless circuit 96, a wireless circuit 98, a battery charger 100, acircuit switch 104, a cordless telephone antenna 106, and a wirelesstelephone antenna 108. Cordless telephone handset 26 may operate as alocal cordless phone for providing cordless telephone operation fromwithin a home or as a wireless telephone providing wireless telephoneaccess from either within the home or outside of the home.

Cordless telephone handset 26 normally operates as a cordless telephonewhen operated in and around the home or business. The telephonycommunication signals that are provided through cordless telephoneantenna 106 are sent to a local terminal, such as subscriber terminal 22shown in FIGS. 1 and 2, so that telephony signals may be exchangedthrough a fiber optic or copper wire-based local loop distributionsystem. The local loop distribution system in turn couples to atelecommunications network. However, when communication is no longerpossible through a local loop distribution system, a cordless telephonehandset 26 converts to wireless mode and telephony communicationcontinues.

In operation, cordless telephone handset 26 is powered by a battery 102that may be recharged by battery charger 100. When operating in localcordless mode and telephony signals are being exchanged through a wiredlocal loop distribution system, common telephone voice circuit 94exchanges signals with in-home cordless circuit 96. Common telephonevoice circuit 94 provides audio signals to speaker 90 and receives audiosignals from microphone 92. In-home cordless circuit 96 exchangessignals with cordless telephone antenna 106 so that wireless telephonysignals may be provided to a local subscriber terminal. Whenever a poweroutage occurs or a failure occurs in the local loop distribution system,telephony signals can no longer be exchanged through a wired local loopdistribution system. Accordingly, cordless telephone handset 26 convertsto wireless mode such that common telephone voice circuit 94 switchesfrom in-home cordless circuit 96 to wireless circuit 98. Conversion towireless operation may occur automatically through detection of a powerloss or manually by a switch on cordless telephone handset 26. Telephonysignals are then exchanged between common telephone voice circuit 94 andwireless circuit 98.

When this change occurs, circuitry switch 104 applies power from battery102 to wireless circuit 98. Wireless circuit 98 provides telephonysignals to wireless telephone antenna 108 so that wireless communicationcan occur between cordless telephone handset 26 and wireless telephoneprovider 14. In this manner, battery power is economically provided forwireless use than for providing back-up power for subscriber terminal 22in the event of a power outage at business/residence 32. Alternative,instead of exchanging wireless telephony signals with a wirelesscommunication system, wireless telephony signals may be exchanged with asatellite-based communication system.

In summary, a subscriber terminal having the capability to exchangetelephony signals with a fiber optic based local loop distributionsystem and with a wireless communication system solves the operationalproblems associated with prior subscriber terminals interfaced to fiberoptic local loop distribution systems when power outages occur. Thepresent invention also provides advantages over the operation ofsubscriber terminals or phones coupled to traditional wire based localloop distribution systems, such as copper-wire local loop distributionsystems, when the local loop system is interrupted, severed, or fails insome manner. Telephony communication can still be provided through awireless communication system.

Thus, there has been provided, in accordance with the present invention,a subscriber terminal and method using a fiber optic based local loopthat satisfies the advantages set forth above. Although the preferredembodiment has been described in detail, it should be understood thatvarious changes, substitutions, and alterations can be made herein. Forexample, different types of wireless communication systems, such assatellite based communication systems, may be used to transfer telephonysignals along with audio, video, and data communication signals. Otherexamples are readily ascertainable by one skilled in the art and may bemade without departing from the spirit and scope of the presentinvention as defined by the following claims.

What is claimed is:
 1. A telecommunications system, comprising: anoptical network unit operable to communicate telephony signals over afiber optic connection; a subscriber terminal operable to exchangetelephony signals with the optical network unit through the fiber opticconnection; and a handset operable to exchange the telephony signalscarried by the fiber optic connection with the subscriber terminal in acordless mode during normal operation, the handset operable to exchangethe telephony signals with a wireless communication system in a wirelessmode upon a loss of power to the optical network unit.
 2. The system ofclaim 1, wherein the optical network unit provides telephony signals tothe subscriber terminal from a telecommunications network.
 3. The systemof claim 1, wherein the optical network unit provides telephony signalsto the subscriber terminal from a wireless telephone provider.
 4. Thesystem of claim 3, wherein the handset communicates with the wirelesstelephone provider upon the loss of power to the optical network unit.5. The system of claim 1, wherein the handset, is operable to exchangetelephony signals with the optical network unit in a wireless mode upona loss of power to the subscriber terminal.
 6. The system of claim 5,wherein the optical network unit provides telephony signals to thehandset from a telecommunications network.
 7. The system of claim 5,wherein the optical network unit provides telephony signals to thehandset from a wireless telephone provider.
 8. The system of claim 1,wherein the handset automatically switches from cordless mode towireless mode upon detecting a loss of power to the optical networkunit.
 9. The system of claim 1, wherein the handset includes a manualswitch in order to place the handset in either the cordless mode or thewireless mode.
 10. A local telecommunications system, comprising: asubscriber terminal operable to exchange telephony signals over a fiberoptic connection; a handset operable to exchange the telephony signalscarried by the fiber optic connection with the subscriber terminal, thehandset operable to function in a wireless mode in order to exchange thetelephony signals with a wireless telephone provider upon detection of aloss of power to an optical source providing the telephony signals onthe fiber optic connection.
 11. The system of claim 10, wherein thehandset automatically switches to wireless mode upon detection of theloss of power to the optical source providing the telephony signals onthe fiber optic connection.
 12. The system of claim 11, wherein thehandset is operable to exchange telephony signals in a wireless modewith the optical source.
 13. The system of claim 12, wherein thewireless telephone provider exchanges the telephony signals with thehandset through the optical source.
 14. The system of claim 13, whereinthe handset exchanges the telephony signals with the optical source,upon detecting a loss of power to the subscriber terminal.